Linear polymers of carbon monoxide and one or more olefinically unsaturated compounds in which monomer units from carbon monoxide and monomer units from the olefinically unsaturated compounds are present in an alternating arrangement can be prepared by contacting the monomers at elevated temperature and pressure with a catalyst suitable for this purpose. These polymers, generally known as polyketone polymers or polyketones, have repeating units of the formula ##STR1## wherein A is a unit derived from at least one olefinically unsaturated hydrocarbon. U.S. Pat. No. 4,880,903 (Van Broekhoven et al.), for example, discloses a linear alternating polyketone terpolymer of carbon monoxide, ethylene, and other olefinically unsaturated hydrocarbons, such as propylene. Processes for production of the polyketone polymers typically involve the use of a catalyst composition formed from a compound of a Group VIII metal, the anion of a strong acid, and a bidentate ligand of phosphorus, nitrogen, or sulfur. U.S. Pat. No. 4,843,144 (Van Broekhoven et al.), for example, incorporated herein by reference, discloses a process for preparing polymers of carbon monoxide and at least one ethylenically unsaturated hydrocarbon using a catalyst comprising a compound of palladium, the anion of a non-hydrohalogenic acid having a pKa of below about 6 and a bidentate ligand of phosphorus.
The preparation of polyketone polymers can be carried out in two ways which, depending on the continuous phase in which the polymerization takes place, are referred to as liquid phase polymerization and gas phase polymerization. In liquid phase polymerization, the continuous phase is formed by a liquid diluent in which the catalyst is soluble but the polymers formed are insoluble or virtually insoluble. At the end of the polymerization, the polymers are separated from the liquid phase and the pure diluent intended for a subsequent polymerization is recovered from the remaining liquid. In gas phase polymerization, the continuous phase is formed by gaseous carbon monoxide and optionally one or more of the other monomers, in so far as they are present in gaseous form in the reactor.
For the preparation of the polymers on a commercial scale, gas phase polymerization is preferred because the liquid phase separation step, as well as the purification step, can be omitted. U.S. Pat. No. 4,778,876 (Doyle et al.), for example, incorporated herein by reference, discloses a gas phase process for the production of polyketone polymers However, some catalysts can exhibit a lower activity in gas phase polymerization than in liquid phase polymerization.
It has been found that the activity of a gas phase polymerization catalyst can be considerably enhanced by introducing an alcohol into the polymerization reactor prior to the polymerization. To attain the desired activity enhancement, introduction of only a small quantity of alcohol is sufficient. The desired effect is also achieved with larger quantities of alcohol, the upper limit being set by the requirement that the continuous phase in which the polymerization takes place is formed by gaseous carbon monoxide and optionally one or more of the other monomers in so far as these are present in the reactor in gaseous form. A drawback of the use of alcohols in the above-mentioned polymerization is that at least a part of the alcohol employed can remain behind in the polymers thus prepared. In the course of continued research on the gas phase polymerization of polyketones, it has now surprisingly been found that the activity-enhancing effect on the catalyst that was previously observed when employing an alcohol is also obtained if water is introduced into the polymerization reactor prior to the polymerization.